1. Field of the Invention
The invention in general relates to water valves, and in particular to such valves that are electrically actuated and are used in appliances such as dishwashers.
2. Description of the Prior Art
Electrically operated water valves have been used for generations in appliances such as dishwashers, washing machines and refrigerator icemakers. Such valves generally have a magnetically responsive armature that alternately turns the water supply on and off as determined by the appliance programming. Such valves also generally include a flow control device which provides a constant water flow rate for all water supply pressures that can be reasonably anticipated. Such flow control devices generally comprise a flexible flow control washer supported by a rigid support. The flow control washer includes a flow control orifice communicating with an aperture in the support. The flow control washer is shaped so that water pressure forcing it against the support causes the flow control orifice to become smaller the higher the water pressure. See for example U.S. Pat. No. 4,651,971 issued to William R. Donahue, Jr., and U.S. Pat. No. 4,815,497 issued to James M. Pick. Also see FIGS. 2A and 2B herein, which show the structure of the flow control portion of the valve of U.S. Pat. No. 4,651,971 in greater detail than shown in the patent. FIG. 2A shows the shape of the flow control washer 46' at low pressures, while FIG. 2B shows the shape at high pressures. Such flow control devices tend to cause the valves to be noisy. Noisy valves are undesirable, especially when used in appliances such as dishwashers and icemakers which often operate during the night. Previous valves have included a bullet 52' which guides the water as it leaves the aperture in the flow control support. See U.S. Pat. No. 4,651,971 and FIGS. 2A and 2B herein. Other valves have included an expansion chamber immediately downstream of the aperture. See U.S. Pat. No. 4,815,497. Both the above valves can be quite noisy at certain pressures and quiet at other water pressures. Both valves may also be noisy if the water is gassy. It would be very desirable to have a valve that is quiet at all water pressures that such valves may reasonably be expected to be exposed to, and even in the presence of gassy water supplies, such as in hot water lines.